Automated weightlifting spotting machine

ABSTRACT

A weight training assistance apparatus which requires a user to overcome the force exerted by one or more weights comprising: one or more sensors for monitoring a user&#39;s activity by monitoring the position of an item indicative of the position of the weights during a weight training exercise; a processor in communication with said sensors; the processor enabled to dynamically compare the user&#39;s activity of the item during the exercise with a predetermined activity profile to determine a dynamic level of fatigue for the user; the processor further enabled to determine a response at a given moment based on the exercise undertaken, the current user activity and the determined dynamic level of fatigue; a load bearing device that is controllable by the processor, the load bearing device enabled to dynamically vary the magnitude of the net force exerted by the weight as determined by the response, the processor further enabled to maintain the magnitude of the force when the user&#39;s activity is within a predetermined limit of the predetermined activity profile.

TECHNICAL FIELD

The invention relates to an automated spotting machine for weightliftingthat applies to both free-weights and stacked weight machines. Thedevice is enabled to provide assistance to a weightlifter when requiredand to bear the load of weight such as a barbell if a user has reachedmuscle failure or the exercise has potentially become dangerous.

BACKGROUND TO THE INVENTION

In weight training it is known for the weightlifter to ask for a spotterto monitor the exercise and to provide assistance to the weightlifterwhen required. The assistance provided may involve taking the wholeweight to avert a dangerous situation when using free weights or toassist with a lift using free weights or stacked weight machines,allowing the weightlifter to continue with an exercise so that they maycomplete more repetitions than they would normally do without assistance(forced repetitions). The assistance of a spotter also allows theweightlifter to perform negative repetitions where the spotter lifts theweight to the starting position and the weightlifter then slowly lowersit whilst being monitored. A spotter may also help the weightlifterperform ‘drop sets’ where once failure has been reached at a givenweight, weights are removed to allow the exercise to continue.

In order to achieve the most effective method for building muscle mass,the lifter should be at the limit of their lifting ability for a periodof time during an exercise session. This limit will vary during thesession since the lifter will progressively fatigue muscle, becomingweaker and more tired as the session progresses.

Without a spotter, the lifter will reach the ‘failure’ point, at whichthey cannot complete a lift, but a spotter can take part of the weightto extend this point so that the lifter can complete more repetitions(reps). It is also known for a lifter who has reached fail to normallycomplete additional assisted reps, example forced or negative reps.

A disadvantage of free weight training is that a spotter is not alwaysavailable and subsequently the user may not partake in free weights ordoes so without a spotter, which is potentially dangerous. Self spottingdevices are known in the art but these rely on the weightlifters inputto provide assistance. For example U.S. Pat. No. 5,823,921 requires theuser to engage a foot pedal to initiate the spotter and is subsequentlycomplex to use.

Another disadvantage of many of the self spotting weightlifting machinesis that they only act as a safety device, and are unable to provideassistance to the weightlifter to help them complete a repetition as isrequired for human spotters.

SUMMARY OF THE INVENTION

The invention seeks to avoid or at least mitigate these and otherproblems in the prior art, the present invention provides an apparatusfor a weight lifting machine, which is able to provide assistance to auser as well as acting as a safety mechanism.

The spotting device is an electro-mechanical system, which can replicatethe role of a human ‘spotter’ in a free weights environment. Thisentails being able to take the full weight of the bar if the lifter isunable to hold it (hence acting as a safety feature) and slightly easingthe weight when the lifter is on the limit of their strength.

In an embodiment of the invention, the main focus is on the latter partof the task. In the present invention, a key aspect is detecting thelevel of fatigue and providing the right amount of support to keep thelifter making maximum use of the muscles. Without a spotter, the lifterwill reach the ‘failure’ point, at which they cannot complete a lift,but a spotter can take part of the weight to extend this point so thatthe lifter can complete more repetitions (reps).

The spotter will use the first rep as a calibration rep, or offer theuser the option of performing a calibration rep. The lifter engages thespotter with a predetermined activity profile, by entering theirpersonal profile and/or enters initial calibration data. Once theapparatus has been calibrated, the lifter performs their exercise, whichis monitored by one or more sensors. A processor is enabled to determinethe lifter's need for assistance and actively support some or all of theweight if required.

In one aspect of the invention there is provided a weight trainingassistance apparatus comprising a sensor for monitoring a user'sactivity during weight training exercise, a processor in communicationwith the sensor adapted to compare the user's activity during theexercise with a predetermined activity profile and to determine theuser's need for assistance, the processor being further adapted tocontrol a load bearing device thereby to assist the user during weighttraining.

According to another aspect of the invention there is provided a weighttraining assistance apparatus which requires a user to overcome theforce exerted by one or more weights comprising: one or more sensors formonitoring a user's activity by monitoring the position of an itemindicative of the position of the weights during a weight trainingexercise; a processor in communication with said sensors; the processorenabled to dynamically compare the user's activity of the item duringthe exercise with a predetermined activity profile to determine adynamic level of fatigue for the user; the processor further enabled todetermine a response at a given moment based on the exercise undertaken,the current user activity and the determined dynamic level of fatigue; aload bearing device that is controllable by the processor, the loadbearing device enabled to dynamically vary the magnitude of the netforce exerted by the weight as determined by the response, the processorfurther enabled to maintain the magnitude of the force when the user'sactivity is within a predetermined limit of the predetermined activityprofile.

Further aspects, features and advantages of the present invention willbe apparent from the following description and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention will now be described by way of exampleonly, with reference to the following drawings, in which:

FIG. 1 is a schematic perspective view of an apparatus in an embodimentof the invention;

FIG. 2 is a schematic side elevation of the apparatus shown in FIG. 1;

FIG. 3 is a schematic of the spotting mechanism;

FIG. 4 is an example of a distance versus time graph of a single rep;

FIG. 5 is an example of a velocity versus time for a single rep;

FIG. 6 is an example of a acceleration versus time graph for a singlerep;

FIG. 7 is a flow chart of the process of the spotting mechanism in use;

FIG. 8 is a schematic perspective view of an apparatus according to afurther embodiment of the invention; and

FIG. 9 is a schematic end elevation of an apparatus according to yetanother embodiment of the invention.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

FIG. 1 shows an embodiment of the invention, in which there is shownapparatus 10, bench 12, rack 14, barbell 16, vertical support 18,pulleys 20, and 24, horizontal support 22, groove 23, motor 42, brake26, motor 25, control panel 28, cable 30, barbell attachment means 32,sensor 34, reflective strips 36, sensor 40, sensor 44 and processor 38(located inside control panel 28).

The apparatus 10 shown in FIG. 1 is a variation of bench pressapparatus. The bench 12, rack 14 and barbell 16 are all standard piecesof equipment. The invention comprises the addition of the verticalsupport 18 and horizontal support 22 which define a structure, whichpreferably extends over the bench 12. Pulleys 20 and 24 are attached tothe horizontal support 22 and pulley 24 is preferably moveable along thegrove 23 powered by motor 25. A motor 26 is attached to vertical support18 and the cable 30 runs from the motor 26, through brake 42, along thevertical support 18, over the pulley 20 along the grove 23 and pulley 24and is attached to the barbell 16 via the barbell attachment means 32.The barbell 16 further comprises reflective strips 36 which allowsensors 40, to sense the barbells vertical position. The sensor 34 movesalong the groove 23 to enable calculation of the horizontal position ofthe barbell 16 and allows the pulley 24 to maintain position above thebarbell 16. Sensor 40 enables calculation of the position of the barbell16. The sensor 34 and sensor 40 are linked to a processor 38, which ispreferably integrated into the control panel 28, attached to thevertical support 18. A control panel 28, which is enabled to displayinformation and allow a user to input information is also integratedinto the vertical support 18. Pulley 24 and sensor 34 move along thegroove 23 by means of a motor 25. The term user and lifter are usedinterchangeably during the course of the specification, and theyrepresent the same person.

The cable 30 is attached to the barbell 16 at barbell attachment means32. The barbell attachment means 32 are preferably releasable allowingthe barbell 16 to be detached from the apparatus and another form of barto be attached. The cable 30 runs from the barbell 16 to pulley 24,along the horizontal support 22 through pulley 20, down the verticalsupport 18 and through the brake 42 to the motor 26. The motor 26 housesthe excess cable 30 and in the preferred embodiment the motor 26provides some resistive force to the cable 30 thereby keeping the cable30 taut. However, the amount of resistive force applied is onlysufficient to keep the cable 30 taut to ensure that the cable 30 doesnot bear any of the load of the barbell 16. The cable 30 is made fromany suitable material that has sufficient strength to be able towithstand a load of a barbell 16, preferably steel wire. For safetyreasons, the cable is preferably able to support several hundred kilos.

The motor 26 in the preferred embodiment is a servomotor though otherforms of motor may be used. The motor 26 is enabled to be able toprovide sufficient power to lift the barbell 16, by retracting the cable30, which is preferably stored in the housing of the motor 26. In thepreferred embodiment, the motor 26 is attached to the vertical support18. In further embodiments (not shown) the motor 26 may placedelsewhere, for example, below the bench 12. A braking mechanism such asa drum type brake is preferably provided within the motor 26. Anadditional brake 42 is provided for additional safety.

The motor 26 therefore is enabled to reduce the net force exert by theweights. Under normal use, the net force of the weights will be theweight (i.e. mass times gravity). When the motor 26 is engaged magnitudeof the net force exerted by the weights is reduced by an amount relatedto the strain taken by the motor. For example, if a barbell 16 has 100Kg of weight and the cable 30 is taut but not bearing any weight the netforce exerted by the weight will be 100 Kg. If the motor 26 is engagedand provides a force of 20 Kg then the net force exerted by the weightsis 80 Kg. Therefore, the magnitude of the net force exerted by theweights can be varied by the motor.

The control panel 28, is enabled to allow the weightlifter to inputdetails regarding themselves e.g. height, weight, arm reach etc., and/orthe exercise they wish to undertake e.g. weight of the barbell 16,number of repetitions, forced or negative repetitions etc. Preferablythe control panel 28 is a self-contained unit of the class typicallyreferred to as a Mobile Data Terminal (MDT) It consists of a computerwith storage, interface cards and a touch screen. It will be operatedthrough a Graphical User Interface (GUI). This device is similar tothose found in-car GPS systems.

In a further embodiment the control panel 28 has other data input meanse.g. USB socket, mobile phone, voice input, swipe card, key fob etc.,which allow the user to identify themselves by some form of externalinput.

The apparatus also contains a number of sensors 34, 40 for calculationof speed and location of the barbell. In the preferred embodiment thereare one or more sensors on rack 14 and one or more sensors 34 located inthe groove 23. In the preferred embodiment the sensors 34 in groove 23are infrared sensors and sensors 40 are infrared or ultrasonic distancemeasuring sensors. The sensors are preferably contactless sensors, thatis to say that they measure the position. The strength of the signalbetween the sensors 34 and 40 allows for a calculation of the positionof the barbell and therefore barbell 16 relative to the vertical support18. Preferably to increase the accuracy of the positional determinationof the barbell 16 there at least two sensors 40 on the rack 14 and atleast one sensor in groove 23.

The sensors 34, 40 may also measure the speed of the cable 30.Preferably there is a barbell sensor 40. In the preferred embodiment thesensor 34 on the horizontal support 22 and the barbell sensor 40 areinfrared sensors enabled to calculate the distance between the sensors34 and 40. As the sensor 34 is fixed and barbell sensor 36 would movethe position of the barbell 16 may be calculated. Other suitable sensingmeans for detecting the position of the barbell 16 with respect to thevertical support 18 may also be used.

All sensors are preferably contactless sensors, that is to say that theymeasure the position of the bar in a 3-D environment without the needfor a physical connection between the measuring sensor and the bar. Thesensors can be used to measure the barbell 16, the weights lifted, thelifting arm etc. The sensors therefore measure the position of an item(e.g. the barbell, the weights, a reflective strip placed on the weightsor barbell etc) which provides an indication of the current position ofthe weights during exercise. The sensors are preferably one or more ofknown infra-red, ultrasonics or laser based sensors

The information from sensors 34, 40 is transmitted to processor 38,which is preferably a suitable known microprocessor. The processor 38 ispreferably integrated into the control panel 28 and is enabled tocalculate the position of the barbell 16 with respect to the verticalsupport 18 from the strength of the signals received from the sensors 34and 40. To accurately measure the position the sensors use triangulationtechniques to accurately measure the position of the barbell 16.

In a further embodiment, there are additional sensors in the horizontalsupport (not shown in FIG. 1) which are used to increase the accuracy ofthe positional measurement.

The processor 38, preferably, is linked to some form of writeable memoryso that it may store information regarding multiple users. The writeablememory may also contain information regarding the user and exerciseprogramme that they are undertaking therefore reducing the amount ofinformation that needs to be inputted at the control panel 28.

FIG. 2 is a side revelation of FIG. 1 and shows the features asdescribed with respect to FIG. 1. A brake 42 and a cable speed sensor 44on the vertical support 18.

A brake is preferably housed in the motor 26, but in a preferredembodiment there is a further brake 42 on the horizontal support 18. Thebrake 42 is preferably a drum brake, though other types of brake may beused. The brake is enabled to stop the cable 30 and is able to supportall the weight of the barbell 16.

FIG. 3 shows a schematic of the control system of the spotter. There isshown the GUI 50, which inputs data to a processor control 52. There isalso shown position sensors 54 and cable tension sensors 56 which inputsinformation to the processor control 52, a brake control 60 whichreceives information from the processor control 52 and an engine control58 and memory 62 which both receive and input data to the processorcontrol 52.

As discussed previously, the control panel 28 is preferably a GUI 50which is enabled to display information and has a touchpad means toallow a user to input further information. In a further embodiment theinformation may be inputted remotely e.g. via a wireless connection, orvia some form of user identifier such as a swipe card, key fob etc. Theinformation inputted at the GUI 50 is passed to the processor controller52.

In a preferred embodiment the controller 52 accesses the memory 62 forany relevant saved data, for example regarding the user, the exercise tobe undertaken. The processor control 52 is preferably further enabled towrite to the memory 62 so that any information inputted at the GUI 50may be stored for further reference.

In the preferred embodiment, the processor control 52 receivesinformation from the position sensors at least 10 times per second, andpreferably between 100-1000 times a second. The information, in the formof signal strength allows the processor control 52 to calculate therelative position of the barbell 16 (not shown in FIG. 3) at thatparticular moment. The processor control 52 stores the differentpositional information over time and therefore can also calculate thespeed and acceleration of the barbell 16. The position and speed of thebarbell 16 are evaluated and if they are outside the accepted tolerancesand decision is made as to whether the brake 42 and/or motor 26 shouldbe engaged. The decision as to whether the position and/or speed areoutside the accepted tolerances is discussed with reference to FIG. 4.

If processor control 52 determines the speed is above an acceptablelimit, the processor control sends a signal to the brake control 60,which engages the brake 42 (not shown in FIG. 3).

If processor control 52 determines the motor 26 should be engaged, theamount of load the motor should bear is calculated by the processorcontrol 52 (The calculation of the load born is discussed with referenceto FIG. 4) and a message is sent to the engine control 58 to wind in thecable 30 to bear the correct amount of load. The speed sensors 54feedback to the controller 52 which in turn feeds back to the enginecontrol 58 to either increase or decrease the load on the cable. Withsuch a feedback loop it is desirable to use a servomotor as the motor26.

In the preferred embodiment the cable 30 is kept taut at all times tominimise the time for the motor 26 or brake 42 to be properly engaged.In further embodiment the cable 30 is slack and a cable tension sensor56 is required. Such a sensor is required to allow the processor control52 to compensate for the slackness in the cable 30. For example if auser drops the weighted barbell 16 the speed sensors 54 would registerthe increase in speed which would be flagged as dangerous the controller52 which would engage the brake 42 via the brake control 60. If thecable 30 is slack the barbell will fall further than if the cable 30were taut. To compensate the controller 52 would, for example, engagethe engine 58 until such time as the tension sensor 56 would registerthe cable 30 as being taut.

In the preferred embodiment the characteristics of freefall will beprogrammed in, so releasing a weight altogether will automatically applythe brake. Also, each site can set a minimum height above the benchbelow which the weight will not be allowed to go. These additionalfeatures are designed to increase the safety of the user.

In use, a user inputs the details of the exercise they wish to performincluding the weight on the barbell 16 and number of repetitions, anddetails regarding themselves e.g. height, arm length into the controlpanel 28.

In a further embodiment the user inputs a unique ID, which will identifythe user, and retrieves previously inputted information about the userfrom a writeable memory 62. The ID preferably also identifies a trainingprogramme for the user and displays the programme to the user at thecontrol panel 28 via the GUI 50. The user indicates via the controlpanel 28 if they wish to accept the suggested exercise or anotherexercise. If the user does not have an ID, the details of the user arepreferably stored on the memory 62 so that the information may beretrieved upon any subsequent use.

In another embodiment the user does not input any information into thecontrol panel and the apparatus is calibrated to the user at the startof the exercise. The calibration in requires the user to perform asingle or multiple presses, where the sensors 34, 40 calculate themaximum height of the barbell 16 during the press which corresponds to afull extension of the user's arms, and the speed of the lift (duringboth ascent and descent). The sensors 34, 40 preferably also recordinformation regarding the height of the barbell 16 through the press, aswell as the time. This allows the processor to construct a model heightversus time graph for an individual press. The sensor information wouldalso be used to construct graphs of various parameters, e.g.acceleration versus time. These graphs are discussed in further detailwith reference to FIGS. 4 to 6.

After input of the data and/or calibration the user performs theirexercise in the normal manner e.g. bench press. Sensors 34 and 40measure the position of the barbell 16 and cable speed sensor 44measures the speed at which the barbell 16 is being moved. The sensors34, 40, 44 send their readings to the processor 38, which usestriangulation techniques to determine the relative position of thebarbell 16.

The speed and positional information is used to determine if theprocessor control 52 is required in engage the brake control 60, to bearall the weight (i.e. the weights exert zero net force) or engine control58 so that the net force exerted by the weights is reduced. The methodand process of determining the course of action and the response isdiscussed in further detail with respect to FIGS. 4 to 6.

FIG. 4 shows an example of a typical height versus time graph for asingle lift.

There is shown the distance S, along the y-axis and time t along thex-axis. The lift is divided into seven stages A,B,C, D, E, F and G.

These seven stages represent, the lifter performing the followingactions:

-   -   A. Accelerating the bar from rest to a maximum velocity;    -   B. Extending arms at maximum velocity;    -   C. Decelerating to lock position at full extension;    -   D. Holding the bar at full extension;    -   E. Accelerating to a maximum descent velocity;    -   F. Holding the fixed velocity for descent; and    -   G. Decelerating to zero velocity at the rest position.

The graph is constructed from the sensor information of the varioussensors 34, 36 placed on the apparatus. The processor 38 is enabled todetermine the position of the barbell 16 at various time intervals.Therefore the processor 38 has position and time data for the barbell16, and the construction of the graph is implemented using standardmethods. In the preferred embodiment, the graph is calculated with arelative position, the baseline being the rest position assumed betweenreps.

From this graph and the associated velocity versus time and accelerationversus time graphs the performance of the user, or lifter, may bedetermined and a decision as to whether to the user requires assistance,and the extent of assistance may be made.

The simplest measurement is distance (S). There is a minimum value (S0)which is the rest position, which corresponds to the lowest position ofthe barbell in a single press. Typically, in a bench press this would bea couple of inches above the user's chest.

There is also a maximum value (SMax), which represents the position forthe arms at maximum extension. The values of S0 and SMax will differaccording to each user and their lifting styles.

The absolute detail of the shape will also vary between lifters, andeven varies between exercises for the same lifter, however, the generalshape and the seven stages are consistent across all weightlifters.

As mentioned previously, there is, for a given lifter, a ‘Calibrationrep’ which is stored in the system (this may, in fact, be the averageover a number of reps). This represents the optimum performance of thatuser, carrying out a single lift when they are unfatigued. Preferably,the calibration rep is performed at the start of each session, as theperformance of a user may change over time. In further embodiments theCalibration rep is stored from previous instances of the user.

The Calibration rep, is known to change between sessions, and within onesession represents the optimum behaviour of the user. In an embodimentof the invention, the first rep of the user is used as the calibrationrep, and the user immediately commences their exercise set.

The spotter detects the onset of fatigue (and hence decides on the levelof assistance) by comparing various parameters of the Calibration repwith the actual performance on a given rep.

The parameters used can be grouped by measurement and stage, where themeasurement is either S (distance), V (Velocity) or A (acceleration).

FIG. 5 shows a typical velocity vs. time graph for a single rep. Theseven stages A to G are equivalent to those described in FIG. 4.

FIG. 6 shows a typical acceleration vs. time graph for a single rep,with the same seven stages as described above.

From the graphs shown in FIGS. 4, 5 and 6 one or more of the followingparameters are determined by the processor 38.

SMax—full extension measured in StageD;

TMax—length of time weight is held at full extension in Stage D, whichare determined from the height versus time graph (FIG. 4).

Vup—velocity achieved in Stage B; Vdown—Velocity achieved in Stage F,from the velocity versus time graph (FIG. 5).

AA—acceleration to maximum lifting velocity (as measure in stage A);AC—deceleration at end of lift (as measure in stage C;) AE—accelerationto descent velocity (as measure in stage E); AG—deceleration to rest (asmeasure in stage G), these are all measured from the acceleration versustime graph (FIG. 6).

The system maintains two variables for the distance, which describepermissible variation in the parameter, these are:

-   -   ΔPN—the normal variation in this parameter which does not        indicate any fatigue; and    -   ΔPF—the failure variation of the parameter which indicates that        the lifter has passed their limit.

An example of the use of ΔPN and ΔPF is given using the velocity Vup,the measured velocity in stage B. From the calibration lift a value ofVup, where the user is assumed to have zero fatigue is calculated. Thisvalue of Vup is expected to decreased during the exercise as the userbecomes fatigued.

By comparing the actual value of Vup to the calibration value of Vup avalue of ΔVup may be determined. The preferred method of determiningΔVup is:

ΔVup=(Vup _(calib) −Vup _(actual))/Vup _(calib)

where Vup_(calib) is the speed of the press in the calibration press andVup_(actual) is the speed during the exercise. Other methods fordetermining ΔVup such as the absolute difference between Vup_(calib) andVup_(actual) may also be used.

In the preferred embodiment the processor 38 uses look up tables todetermine a course of action based on the value of ΔVup. For example ifthe value of ΔVup is 0.1 this would indicate that the user is performingthe lift 10% slower than during the calibration rep. Such a value in thelook up table would be marked with ΔVupN or ΔPN i.e. that the user hasnot reached failure. Accordingly the processor 38 would continuemonitoring the exercise and allow the user to continue as normal.

If at a later time, say after the 10th rep, the value of ΔVup is 0.66,this would indicate that the user is becoming fatigued and may requireassistance. In this example the look up table for 0.66 would read ΔVupFor ΔPF i.e. the user has reached failure and requires assistance. Theprocess of assisting the user is described below with reference to FIG.7. The above measurement of the variation between the model and theactual behaviour and the monitoring of the values of ΔP may be appliedto one or more the parameters listed above and not just Vup.Additionally, the look-up tables may be tailored to the individual user,depending on the extent of the exercise they wish to do, with the valuesof ΔPN and ΔPF changing accordingly.

In a further embodiment, the profiles that are stored in the writeablememory 62 also contains a “problem pattern” library. The librarycontains profiles which are indicative of current types of “non-ideal”lifts. The term non-ideal relates to where a lift is not performed inthe idealised manner, for example, where one arm is favoured overanother arm, the barbell 16 may rotate slightly. By analysing theperformed exercises against the “problem library” the invention is ableto identify if any lifts are being performed incorrectly. Preferably,the invention is able to communicate this to the user by way of the GUI50.

FIG. 7 is a flow chart of the process of the spotter algorithm that thecontroller 52 uses to evaluate if a user requires assistance. There isshown the monitoring the speed and position at step S100, updating thevarious graphs at step S102, calculating the value of ΔPN and ΔPF atstep S104, determining if the user requires assistance at step S106,engaging the motor and or brake at step S108, The monitoring of thespeed and position of the barbell 16 at step S100 is performed using thevarious sensors 34,40, 44 which inputs the data to the processor 38. Theprocessor 38 determines the position of the barbell 16 as well as thetime. The information is stored in the processor during the exercise.

The monitoring of the speed and position of the barbell preferablyoccurs at least 10 times a second and preferably between 100-1000 timesa second for safety reasons. This allows for any potentially dangeroussituation to be quickly identified, and the apparatus to react toprevent any injury to the user.

Using the information recorded at step S100, the various graphs areupdated at step S102. In the preferred embodiment, the graphs that areupdated are the distance vs. time, velocity vs. time and accelerationvs. time graphs. From the position and time information the updating ofthe graphs is readily implemented by the processor 38.

Using the updated graphs from step S102 the values of AP, where P isparameter e.g ΔVup, are updated at step S104. The determination of thevalues of ΔP is as described above.

Once the values ΔP has been determined it is compared to the value ofthe look up table at step S106. If a value of ΔPF is returned it is anindication that the user has reached muscle failure or is fatigued andtherefore requires assistance, the process goes to step S108. If ΔPN isreturned the user is within the acceptable limits and the processreturns to step S100 and repeats until failure has been reached or theexercise is finished. By monitoring the speed and position several timesa second, values of ΔP may be dynamically updated. i.e. they are updatedwhenever a measurement is taken. Therefore, measures of fatigue andfailure may be dynamically determined during user exercise. Preferablystep S106 is performed upon each measurement of the position of theweights by the one or more sensors, and therefore occurs at least 10times per second, preferably more. Therefore the apparatus may beconsidered to be dynamically varying the weight, in that the variationsoccur at a rate such that the user is unable to notice a pause betweenoperations.

If the user requires assistance the amount of assistance required iscalculated and the motor and/or brake is engaged at step S108.

The amount of work performed by a user during a single lift isproportional to the area under a distance versus time graph, as shown inFIG. 4. Such work may be represented as a power curve for the exercise.The power curve varies with the amount of power required for theexercise at a given time. e.g. More power is required at the start of alift than say at the top of the lift. Power curves will vary for eachuser and for the exercise undertaken. In a further embodiment fatigueand muscle failure may be measured using the power curve profile.

If the user requires assistance the speed of the lift is below theaccepted tolerance the amount of load to be taken by the cable iscalculated as being proportional to the weight on the barbell 16 and thedifference between the area under the graph of the model graph and theactual graph. So if the actual relative height of the barbell 16 is muchlower than the expected height the difference of the areas would belarge and the processor control 52 would send a signal to the enginecontrol 58 to increase the power of the motor 26 thereby increasing theload on the cable and reducing the net force exerted by the weights.

When the system detects fatigue it has the option depending upon userpreference, to engage one of four exercise regimes: 1 forced reps; 2negative reps; 3 drop sets; 4 partial reps.

For all types of additional reps the user will have reached the point ofpositive muscular fatigue.

Forced Reps;

Forced reps require a training partner to provide just enough assistanceto keep the weight moving. This continues for the desired amount ofrepetitions.

The equivalent behaviour for the invention is as follows. The inventiontracks the behaviour of the user to determine if they are in a fatiguezone (as described below). If they are fatigued then the system liftsjust sufficient weight from the bar to enable the user to keep operatingwithout entering the failure zone. The invention continually monitorsand re-calculates the required assistance during the exercise thuskeeping the user at the edge of positive muscle failure. Therefore, themotor dynamically varies the net force exerted by the weights throughthe motor until the user is within the limit of positive muscle failure.

If the user is found to be in the failure zone the weight is dynamicallyreduced until such time the user is able to lift the weights and theyare no longer considered to be failing. Once the user has reached thefatigue zone (i.e. moved out of the failure zone) the motor maintainsthe net force so that the user may continue the exercise with weightsexerting a reduced net force.

This is continued until the desired number of reps are completed.

Negative Reps;

Negative reps require a training partner to lift the weight to the startposition at maximum extension (SMax). The user simply lowers the weightas slowly as possible. When the user reaches the bottom of the movement,(SMin) the training partner will raise the weight again. This continuesfor the desired amount of repetitions.

The equivalent behaviour for the invention is as follows. The inventionautomatically raises the weight to the maximum extension (SMax) for thisuser by engaging the motor 26 to take the full weight of the barbell 16.The user then takes the weight of the barbell 16 and lowers it to theirminimum position (SMin). The invention tracks this behaviour andprovides safety feature to lift the weight if it is being lowered in anuncontrolled manner. At the bottom of the rep it lifts the weight to thetop and repeats until the desired number of reps are completed.

During descent, as with the forced reps scenario, if the user is foundto be beyond the limit of positive muscle fatigue the motor willdynamically reduce the net force exerted by the weights until the useris determined to be within the fatigue zone. As with the force reps oncethe user has moved back into the fatigue zone the net force exerted ismaintained.

Drop Sets;

For drop sets the user performs a set of any exercise to failure or apoint just short of failure. At this point the weight is reduced and theuser continues for more repetitions with the reduced weight.

The equivalent behaviour for the invention is as follows. The inventiontracks the behaviour of the user until the fatigue zone is entered. Atthis point it reduces the weight by a pre-determined percentage andcontinues to track the user as with normal reps. The pre-determinedpercentage may be user inputted when initialising the apparatus or itmay be a set percentage. The dropped weight may be by either physicallychanging the weights on the barbell 16 or using another barbell 16, orby engaging the motor 26 to bear the pre-determined weight during thelift.

As with the forced rep scenario, if the user is unable to maintain theirexercise level with the dropped set (i.e. stay within the limits ofpositive muscle failure) the motor will dynamically reduce the net forceexerted by the weight until the user is able to perform their exerciseat the predetermined acceptable level.

Partial reps

Partial reps occur when the user intentionally completes less than thefull extension for a rep while using a given weight on the bar. Thepartial is typically the top part or the bottom part of the normal fullrep. The user will decide how much of a rep to complete and whether itis top or bottom. Typically, the partial rep will be inputted into thecontrol panel by the user at the start of the exercise. In a furtherembodiment the partial rep to be performed will be stored in the user'sprofile.

When performing a partial rep with a human spotter the exercise occursas follows. If the top part of the rep is to be completed the trainingpartner holds the bar at the starting position. The user lifts fromthere to the top of the rep in an unassisted manner, and then returnsthe weight to where it started, at which point the training partnertakes the weight from them. If it is the lower part of the rep then theuser starts from their normal SMin and lifts until the spotter tellsthem that they have reached their desired extension.

The equivalent behaviour for the invention is as follows. The inventioncan be configured to provide either Upper or Lower partial reps. Theuser must choose the type of rep and the range of the rep (i.e. thedistance between bottom and top of the rep).

For upper partial reps, the invention moves the weight to a positionwhich is below SMax by the value of range of the rep. The user takes theweight, lifts it to the top and lowers it. When the weight reaches theposition which is below SMax by the value of range, the invention takesthe full weight.

For lower partials, the system treats the rep like a normal rep, exceptthat it takes range, rather than SMax to be the top of the rep. In thepreferred embodiment there is an auditory confirmation, such as a siren,is used when this position is reached.

In a further embodiment the look up tables are used to determine theamount of assistance required. From the example of ΔVup in FIG. 6, ΔVupwas 0.66, the look-up table also contains an indication of how muchweight should be beared by the cable 30 and motor 26. The value of 0.66would indicate that whilst the user is tired they still have not reachedtotal muscle failure and accordingly the motor 26 and cable 30 will take10% of the total weight of the bar. The higher the value of ΔVup, themore fatigued the user and therefore the greater the weight born. As asafety aspect if the value of ΔVup reached 80% the motor and cable wouldtake the entire weight of the barbell 16 as the user would have reacheda dangerous level of muscle failure and may potentially lose control ofthe barbell 16. Again the value of the percentage of weight to be takenby the motor as defined in the look-up tables may be varied.

The power supplied by the motor 26 is, in a preferred embodimentconstantly adjusted, to take into account the user performance when theengine is engaged. The values of ΔPN and ΔPF are re-calculated whilstthe assistance from the motor 26 occurs. If the value of ΔPN is found toreturn to within the acceptable limits it would indicate that thecorrect amount of assistance is being provided and that level ofassistance is maintained. If the value of ΔPF increases whilst the motor26 is engaged, it would indicate that the user requires furtherassistance and the processor control 52 would send a signal to theengine control 58 to further increase the power supplied. The level ofassistance (i.e. reduction in net force) is increased until such timethat the user is within the pre-determined zone e.g. the values of ΔPNand ΔPF are within the acceptable limits. Once the user is within theacceptable limits then the present level of assistance is maintained.

Drop Sets;

In yet another embodiment of the invention, if the user is found torequire assistance the apparatus may enter “drop weight” mode. Once theuser has reached failure on a particular weight set, the rep iscompleted and the barbell 16 returned to the rack 14. Weights are thenremoved from the barbell 16, and a further set of reps are completedusing the lower or dropped weight set.

In yet another embodiment of the invention, if the user is found torequire assistance the apparatus may enter “drop weight” mode. Once theuser has reached failure on a particular weight set, the rep iscompleted and the barbell 16 returned to the rack 14. Weights are thenremoved from the barbell 16, and a further set of reps are completedusing the lower or dropped weight set.

In a further embodiment, the motor 26 is used to simulate the removal ofthe weight from the barbell 16, during the “drop weight” mode. In thisembodiment, the cable 30 is kept taut and the motor 26 is engaged tobear some of the load of the barbell 16. For instance, a user completes20 reps using a 60 kg weight, and is found that their value of ΔPFindicates that they have reached fail after 10 reps. The motor 26 isengaged and supplies sufficient power to constantly lift 10 kg.Therefore the motor 26 has effectively reduced the weight on the barbell16 to 50 kg. The user continues with their reps and is found to fail,from their measured value of ΔPF after a further 5 reps at 50 kg. Themotor 26 increases the load born by a further 10 kg, effectively makingthe weight on the barbell 40 kg. This allows the user to complete theirexercise without having to rack the barbell and remove some weights, aswould occur when normally performing free-weight exercises. The settingof the drop weight mode is preferentially preformed at the control panel28, where the increments in the reduction of weight may be set, thoughit may also be activated as part of a user profile stored in thewriteable memory 62.

A further indicator of a user requiring assistance is if the relativeheight of the barbell 16 begins to decrease before maximum extension isreached. This indicates that the user has reached muscle failure and theprocessor control 52 is required to engage engine control 58 as a safetyfeature. The load that the cable 30 would bear in this situation in anembodiment is calculated by the value of ΔPF. In a further embodimentthe power of the motor 26 and therefore the load beared is taken asbeing proportional to the weight of the barbell 16 and the differencebetween maximum height achieved and the maximum expected height. Again,if the difference is large the processor control 52 increases the powerof the motor 26 thereby increasing the load on the cable and reduces thenet force exerted by the weights.

The motor 26 is engaged at step S108 winding in the cable 30 to take theload as required. Once the motor 26 is engaged the speed and height ofthe barbell 16 are continually monitored. If, in the case of the speedfalling below a set tolerance, the difference in the area between themodel and actual graphs increases, it would indicate that moreassistance is required and the motor 26 increases its load borne. If thespeed increases to above the expected speed the load bared by the motor26 will decrease, as it would indicate that the user requires lessassistance. Therefore, once the motor has been engaged to vary the netforce exerted by the weights, the process returns to step S106 tomonitor the user's exercise. If the user is still found to requireassistance at step S106 the process repeats until the user is found tobe within an acceptable limit of the predetermined user profile.Therefore, the power exerted by the motor 26, and therefore thereduction in the net force, is continually varied until such time theuser is within an acceptable limit i.e. is found not to requireassistance as determined at step S106.

As a further safety mechanism, if the barbell 16 is travelling downwardsthe speed at which it is travelling is checked against a maximum safespeed and preferably acceleration. Given the position and timeinformation the processor is able to measure the speed and accelerationof the barbell 16. If the barbell 16 exceeds the maximum safe speed oracceleration it would indicate that the user is unable to control thebarbell 16 and the controller 52 engages the brake. Preferably as wellas engaging the brake the motor 26 will also be engage to lift thebarbell 16.

In yet another embodiment, further monitoring of the user may also occurby measuring the rise time, sections A, B and C of FIG. 4, the fall timesections E, F and G of FIG. 4 and the pause time which is simply theperiod of time between reps. As a user completes more repetitions it isfound that the pause time increases as the user becomes fatigued. If thepause time is measured to increase to a level greater than expected,this would be taken as an indication that the user may requireassistance. In an embodiment of the invention there is a maximum pausetime which if exceeded would automatically engage the motor 26. Themaximum pause time may be set by the user at the control panel 28 wheninitialising the invention or be a default setting of 20 seconds.

Other free-weight exercises will have different shaped graphs, and theprocessor 38 would react according to these graph shapes. In a furtherembodiment the graph shapes for the individual users are stored on thewriteable memory 62 allowing the processor 38 to compare the height andspeed against previous user data rather than model data. If a modelheight versus time graph is used it would be stored in the memory 62 andpreferably accessed by the processor 38 during the initialising of theapparatus 10.

In a further embodiment of the invention the control panel is enabled toaccept voice commands. As well as monitoring the user in the mannerdescribed above the invention may accept commands from the user such as“Spot” or “Help” to engage the motor 26 and “more” or “less” control theamount of load to be supported by the motor. This embodiment relies onstandard voice recognition techniques to determine that assistance isrequired.

Whilst the present invention has been described with respect to thebench press exercise as shown in FIG. 1, those skilled in the art willunderstand that the present invention need not be limited to the benchpress but is also applicable to all other forms of free weightliftingsuch as an inclined barbell press, dumbbell flyes, standing barbellpress, dead-lifts etc, as well as stacked weight machines andphysiotherapy equipment where the weight taken by the invention is thatof the users limb or body. Other weight exercises and applications willhave different shaped graphs, but the processor 38 calculation of ΔPFand ΔPN would be performed in an identical manner, of using acalibration rep and comparing the actual data to the calibration dataand making decisions based on the comparison as described above.

FIGS. 8 shows a further embodiment of the apparatus. There is shown thefeatures of the apparatus as described in FIGS. 1 and 2.

In this embodiment there are two motors 26, each with pulleys 20 andcable 30. The cables 30 are attached at opposite ends of the barbell 16.In this embodiment, the motors 26 are configured to provide differentamounts of support on each side of the barbell 16. This may be requiredwhen one of the user's arms reaches fatigue or failure before the other.The method for determining if a user is reaching fatigue or failure isas described above.

In a preferred embodiment, the processor also places a limit on thedifferential between the supporting forces provided by each motor 26thereby ensuring that the user does not preferentially use one arm overanother.

FIG. 9 shows yet another embodiment of the apparatus. There is shown thefeatures of the apparatus as described in FIGS. 1 and 2. There is alsoshown a track 51.

The vertical supports 18 are moveable along the tracks 51. The supports18 are moved using a pulley and cable system (not shown) though othermethods may be used. Depending on the exercise to be performed thetracks 51 may be positioned to move the vertical supports 18 in thedirection of the exercise. For example, in a “pullover” type exercise,the lifter lies on their back and weights are moved from abdomen toabove their head, the weights move both vertically and horizontally, asopposed to a “bench press” where the weights move vertically. Thevertical supports 18 are moveable to ensure that the support is abovethe barbell 16 during the exercise. In further embodiments the supports18 are fully moveable in the x-y axis thus ensuring that the supports 18are above the barbell 16 for all range of motions.

1-40. (canceled)
 41. A weight training assistance apparatus whichrequires a user to overcome the force exerted by one or more weightscomprising: one or more sensors for monitoring a user's activity bymonitoring the position of an item indicative of the position of theweights during a weight training exercise; a processor in communicationwith said sensors; the processor enabled to dynamically compare theuser's activity of the item during the exercise with a predeterminedactivity profile to determine a dynamic level of fatigue for the user;the processor further enabled to determine a response at a given momentbased on the exercise undertaken, the current user activity and thedetermined dynamic level of fatigue; a load bearing device that iscontrollable by the processor, the load bearing device enabled todynamically vary the magnitude of the net force exerted by the weight asdetermined by the response, the processor further enabled to maintainthe magnitude of the force when the user's activity is within apredetermined limit of the predetermined activity profile.
 42. Theapparatus of claim 41, wherein the item indicative of the position ofthe weights are the weights used during the exercise.
 43. The apparatusof claim 41, wherein the dynamic comparison to determine user activityis a comparison of the position of the item.
 44. The apparatus of claim41, wherein the processor is further enabled to determine a level ofmuscle fatigue based on the dynamic comparison of user activity and thepredetermined profile and determines the response based on useractivity, fatigue and failure.
 45. The apparatus of claim 41, whereinthe predetermined activity profile is a user specific profile for theweight training activity undertaken by the user.
 46. The apparatus ofclaim 41, wherein the comparison is substantially a real-timecomparison, and the determination of the response is in substantiallyreal-time.
 47. The apparatus of claim 41, wherein the response tofatigue is one or more of the following: the load bearing device varyingthe magnitude of the net force exerted by the weight to zero; the loadbearing device varying the magnitude of the net force exerted by theweight wherein the net force exerted by the weight is reduced by anamount proportional to the level of fatigue detected.
 48. The apparatusof claim 41, wherein where the load-bearing device is a motor, and wherethe apparatus further comprises a braking mechanism coupled to the cableand wherein the processor is enabled to control one or more of thespeed, torque and braking of the motor.
 49. The apparatus of claim 41,wherein the processor is further enabled to compare of the user activityagainst one or more profiles, which form a pattern profile library todetermine if the user activity is indicative of a particular patternprofile wherein the pattern profile library contains known incorrectlifting profiles thereby allowing the identification of incorrectlyperformed lifts.
 50. The apparatus of claim 41, wherein the one or moresensors are contactless sensors selected form the group of: infra-red,ultrasonic or laser based sensors.
 51. The apparatus of claim 41,wherein the level of assistance provided by said load bearing devicevaries according to a measure of the divergence between thepredetermined activity profile and the actual user activity.
 52. Theapparatus of claim 41, where the decision to engage the load bearingdevice is based on a comparison of the relative position, velocity oracceleration of the weight compared to an expected position based on apre-determined model.
 53. The apparatus of claim 41, further comprisinga form of writeable memory and where data regarding previous exercisesperformed on the apparatus is stored on the writeable memory and whereinthe model is based on historic data of previous instances of the same orsimilar exercise, preferably by the same user.
 54. The apparatus ofclaim 41, wherein the processor is enabled to compare one of more of thefollowing of a user's activity against the predetermined activityprofile: full extension of the user during the exercise; time betweenrepetitions; velocity of the weights.
 55. The apparatus of claim 41,wherein the processor is enabled to determine if the user has reachedfailure, where the comparison of the user's activity and predeterminedprofile is beyond a predetermined limit and further comprising a safetymechanism to bear the entire load wherein the safety mechanism isenabled by the processor in response to high level of fatigue or failureas determined by the processor.
 56. The apparatus of claim 41, whereinthe apparatus further comprises one or more additional motors, saidmotors selectively engaged to provide different levels of lift to reducethe net force exerted.
 57. A method of self-spotting weightlifting themethod which requires to overcome the force exerted by one or moreweights comprising; attaching a load bearing means to one or moreweights; exercising with the weights attached to the load bearing means;monitoring the position of an item indicative of the position of theweights through one or more sensors; determining if a user requires helpby comparing the position of the item to a pre-determined model;selectively engaging the load bearing means to dynamically vary themagnitude of the force exerted by the weights in response to thedetermining step until such time that the user is determined to nolonger require assistance; and maintaining the magnitude of the netforce exerted once the user is determined not to require furtherassistance.
 58. The method of claim 57, further comprising the step of:determining a parameter associated with the item; determining if theparameter was within a predetermined limit of the predetermined model,and in the event that the parameter is outside of the selectivelyengaging the load bearing means.
 59. The method of claim 58, wherein theparameter associated with the item is one of: position, velocity,acceleration.
 60. The method of claim 57, wherein the method furthercomprises storing information regarding completed exercises to a form ofwriteable memory.